During the last several years we have been able to breed an inborn strain of rats which develop a syndrome close to that observed in human diabetes mellitus including renal and retinal microangiopathy. The objectives of the present project are to study in vivo the involvement of collagen in this diabetic syndrome. The various aspects of collagen metabolism in the different tissues, such as aorta, heart, kidney, bone, cartilage, skin and tendon will be studied using a variety of methods including radioisotope labelling, the diffusion chamber technique which has been adopted for in vivo collagen studies by the principal investigator, radioimmune assays and immunofluorescent techniques etc. The data obtained from the collagen studies will be correlated with those obtained from the biochemical and histopathological examinations. One of the objectives of this study is to verify a hypothesis about the genetically determined aberrations in collagen biosynthesis in diabetes.